1990 4.0 Spark Plug Gap - JeepForum.com

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post #1 of 4 Old 10-06-2007, 11:56 AM Thread Starter
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1990 4.0 Spark Plug Gap

I'm changing the plugs on my '90 cherokke tomm. it has a 4.0 in it and I was wondering what the GAP on the plugs should be. Thanks

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post #2 of 4 Old 10-06-2007, 11:57 AM
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(FYI- sticker in your engine compartment should have this info on it. Up on the firewall on the drivers side. If I remember correctly).

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post #3 of 4 Old 10-06-2007, 12:09 PM Thread Starter
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thanks alot
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post #4 of 4 Old 10-06-2007, 02:42 PM
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try autolite 3924, regular reach, old-school style spark plugs.

the long-reach plugs recommended in most books are TOO hot of plug (rough idle misfire) this includes autolite 985 and champion R12YC plugs...those are all long reach and if you have a rough idle when motor is warmed up...caused by too hot heat range long-reach plugs.

go to store and look at all these plugs...you'll see what i mean.

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